1. Field of the Invention
The invention relates to a method for operating an apparatus for acquiring the location of at least one characteristic area of a person and for generating a control signal for a device dependent on this location.
2. Description of the Related Art
German Patent DE 27 40 908 discloses an x-ray diagnostics means for transillumination and provides a means for acquiring the viewing direction of an observer. The means is connected to a control device for varying the direction of the central ray of a ray beam emanating from an x-ray source, so that the direction of the central ray can be modified dependent on the viewing direction of the observer.
The periodical Bild der Wissenschaft, Nr. 3, 1977, page 27, published a report under the title "Blick ins Auge" according to which scientists of the Radiation Center of Honeywell (Lexington/USA) have developed a device that makes it possible to acquire, to register and to visualize the viewing direction of a test person as preciseley as possible. An infrared light beam is directed onto the eyes of the test person and a special video camera registers each eye movement. The information identified in this way are supplied to a mini-computer that calculates the respective position of where the person is looking and allows this to appear on a picture screen as a visible point. The scene observed by the test person can be seen on the same picture screen. The "remote oculometer" allows the direction of view to be acquired without deteriorating normal eye movements. This system is used in the USA in the Air Force, the Marines, in NASA and in commercial air traffic. It serves both training purposes, namely improving the ability of the observer to concentrate, as well as design purposes for determining better designs of cockpits, instrument panels and similar devices. Further areas of application are opened up in reviewing the effectiveness of advertising in television programs, in the registration of recognition possibilities in road traffic and in determining learning disabilities in children.
German Patent DE 195 41 301 provides a controlling means for acquiring what an observer has focused on and observed on a display means observed, whereby the means controlling generate a signal for controlling the display means such that the resolution of the display means in the observed area is higher than in the non-observed area of the display means.
In such devices for acquiring the viewing direction or what an observer has focused on, it is mainly the eyes of the person that are utilized, and the direction of view is acquired on the basis of the alignment of the pupil in the eye. The image signals of the eye registered by a camera are interpreted by an image computer and converted into control signals. However, since the recognition of the pupil from the image signals of a camera, is an extremely complicated procedure, a high calculating performance of the computer unit is required. Such computer units are expensive since they must work with large data sets generated from the image signals in an optimally short time. The required computing power is significantly greater than available in current PCs. The application of such a means is therefore limited to few areas of employment.
A device for detecting the pupil movement for controlling, in particular, a computer on the basis of a menu is previously known from Ebisawa, Y., "Unconstrained Pupil Detection Technique using Two Light Sources and the Image Difference Method", Visualization and Intelligent Design in Engineering and Architecture II, Proceedings of 2nd International Conference on Visualization Tools for Intelligent Design in Engineering and Architecture, La Coruna, Spain, June 1995, ISBN 1-85312-319-5, 1995, Southhampton, UK, Comput. Mech. Publications, UK, pages 79-89, XP002052717. The apparatus in this referance uses two light sources that are implemented as infrared light sources and are arranged at an angle relative to one another, as well as a video camera in combination with a computer unit that subtracts the image signals of the light sources driven in alternation from one another in order to generate difference image signals. This apparatus differs from the subject matter of the present application in that the light sources according to the reference have the same light emission. The subject matter of the present application is therefore not known from the reference, nor is there an obvious teaching thereof.
Using only a single infrared light source for generating image signals for detecting eye movement is known from Ebisawa, Y. et al., "Non-invasive Eye-gaze Position Detecting Method Used on Man/Machine Interface for the Disabled", Computer based Medical Systems, Proceedings of the Fourth Annual IEEE Symposium, Baltimore, Md. USA, May 12-14 1991, ISBN 0-8186-2164-8, 1991, Los Alamitos, Calif., USA, IEEE Comput. Soc. Press, USA, pages 374-380, XP000350289, Section "2.2.2 Camera Rotation system".
U.S. Pat. No. 4,950,069 discloses a device for detecting the eye movement and for generating a control signal for a computer. In combination with only a single infrared light source, an infrared camera generates image signals that are processed in a computer for generating the control signals.